[v6.6] KASAN: slab-use-after-free Write in rose_t0timer_expiry

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Mar 1, 2026, 6:01:28 PM (3 days ago) Mar 1
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Hello,

syzbot found the following issue on:

HEAD commit: 7a137e9bfa0e Linux 6.6.127
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=141c4952580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2a950bf7c0bff9f9
dashboard link: https://syzkaller.appspot.com/bug?extid=d211a8194a959c8ebeba
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/04a02efb4a79/disk-7a137e9b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7b848f192f0/vmlinux-7a137e9b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/77a981f90b3d/bzImage-7a137e9b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d211a8...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in rose_t0timer_expiry+0x23e/0x350 net/rose/rose_link.c:85
Write of size 1 at addr ffff88802705cc35 by task dhcpcd-run-hook/17578

CPU: 1 PID: 17578 Comm: dhcpcd-run-hook Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
<IRQ>
dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xa8/0x210 mm/kasan/report.c:468
kasan_report+0x117/0x150 mm/kasan/report.c:581
rose_t0timer_expiry+0x23e/0x350 net/rose/rose_link.c:85
call_timer_fn+0x189/0x540 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1752 [inline]
__run_timers+0x542/0x800 kernel/time/timer.c:2023
run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:orc_ip arch/x86/kernel/unwind_orc.c:80 [inline]
RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:102 [inline]
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:227 [inline]
RIP: 0010:unwind_next_frame+0x4a3/0x2970 arch/x86/kernel/unwind_orc.c:494
Code: 74 24 48 48 89 d8 4c 29 e0 48 89 c1 48 c1 f9 02 48 c1 e8 3f 48 01 c8 48 83 e0 fe 4d 8d 3c 44 4c 89 f8 48 c1 e8 03 0f b6 04 10 <84> c0 75 3e 4d 63 2f 4d 01 fd 4c 89 ef 4c 89 f6 e8 48 dc 4b 00 49
RSP: 0018:ffffc900039d7438 EFLAGS: 00000a06
RAX: 0000000000000000 RBX: ffffffff8ea1eaa8 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 000000000002a57c RDI: 000000000002a57d
RBP: ffffffff8ea1eaa8 R08: ffffc900039d75d0 R09: 0000000000000004
R10: 0000000000000004 R11: 0000000000000000 R12: ffffffff8ea1eaa8
R13: 000000000002a57c R14: ffffffff81ce5e68 R15: ffffffff8ea1eaa8
arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
save_stack+0x125/0x230 mm/page_owner.c:128
__reset_page_owner+0x4e/0x190 mm/page_owner.c:149
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1181 [inline]
free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2365
free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2504
release_pages+0x1f7a/0x2200 mm/swap.c:1022
tlb_batch_pages_flush mm/mmu_gather.c:99 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:294 [inline]
tlb_flush_mmu+0x379/0x510 mm/mmu_gather.c:301
tlb_finish_mmu+0xf9/0x220 mm/mmu_gather.c:425
exit_mmap+0x428/0xb90 mm/mmap.c:3315
__mmput+0x118/0x3c0 kernel/fork.c:1355
exit_mm+0x1f2/0x2c0 kernel/exit.c:569
do_exit+0x8dd/0x2460 kernel/exit.c:870
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
__do_sys_exit_group kernel/exit.c:1035 [inline]
__se_sys_exit_group kernel/exit.c:1033 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1033
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f709503e6c5
Code: Unable to access opcode bytes at 0x7f709503e69b.
RSP: 002b:00007ffced1b82f8 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007ffced1b8604 RCX: 00007f709503e6c5
RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000
RBP: 0000000000000003 R08: 00007ffced1b83f0 R09: 0000000000000002
R10: 00007f70950e4fe0 R11: 0000000000000202 R12: 0000000000000000
R13: 00007ffced1b8630 R14: 00007f7095246000 R15: 000056270d6e3d98
</TASK>

Allocated by task 10957:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
____kasan_kmalloc mm/kasan/common.c:375 [inline]
__kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
kmalloc include/linux/slab.h:600 [inline]
rose_add_node+0x23c/0xf00 net/rose/rose_route.c:85
rose_rt_ioctl+0xd2c/0x1290 net/rose/rose_route.c:748
rose_ioctl+0x3fc/0x8f0 net/rose/af_rose.c:1381
sock_do_ioctl+0xfc/0x310 net/socket.c:1219
sock_ioctl+0x5ba/0x7e0 net/socket.c:1340
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 16154:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1811 [inline]
slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837
slab_free mm/slub.c:3830 [inline]
__kmem_cache_free+0xba/0x1e0 mm/slub.c:3843
rose_neigh_put include/net/rose.h:166 [inline]
rose_timer_expiry+0x4c6/0x5f0 net/rose/rose_timer.c:183
call_timer_fn+0x189/0x540 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1752 [inline]
__run_timers+0x542/0x800 kernel/time/timer.c:2023
run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687

Last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:46
__kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
__call_rcu_common kernel/rcu/tree.c:2721 [inline]
call_rcu+0x153/0x950 kernel/rcu/tree.c:2837
kthread_worker_fn+0x4d4/0xa80 kernel/kthread.c:843
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Second to last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:46
__kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
insert_work+0x3d/0x310 kernel/workqueue.c:1651
__queue_work+0xd2c/0x1020 kernel/workqueue.c:1804
call_timer_fn+0x189/0x540 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1747 [inline]
__run_timers+0x56d/0x800 kernel/time/timer.c:2023
run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687

The buggy address belongs to the object at ffff88802705cc00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 53 bytes inside of
freed 512-byte region [ffff88802705cc00, ffff88802705ce00)

The buggy address belongs to the physical page:
page:ffffea00009c1700 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2705c
head:ffffea00009c1700 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017c41c80 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2474, tgid 2474 (kworker/u4:0), ts 10062567344, free_ts 0
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1581
prep_new_page mm/page_alloc.c:1588 [inline]
get_page_from_freelist+0x1951/0x19e0 mm/page_alloc.c:3220
__alloc_pages+0x1f0/0x460 mm/page_alloc.c:4486
alloc_slab_page+0x5d/0x160 mm/slub.c:1881
allocate_slab mm/slub.c:2028 [inline]
new_slab+0x87/0x2d0 mm/slub.c:2081
___slab_alloc+0xc5d/0x12f0 mm/slub.c:3253
__slab_alloc mm/slub.c:3339 [inline]
__slab_alloc_node mm/slub.c:3392 [inline]
slab_alloc_node mm/slub.c:3485 [inline]
__kmem_cache_alloc_node+0x19e/0x250 mm/slub.c:3534
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:721 [inline]
alloc_bprm+0x56/0x9b0 fs/exec.c:1538
kernel_execve+0x98/0x9c0 fs/exec.c:2023
call_usermodehelper_exec_async+0x20b/0x350 kernel/umh.c:110
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
page_owner free stack trace missing

Memory state around the buggy address:
ffff88802705cb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802705cb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802705cc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802705cc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802705cd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 74 24 je 0x26
2: 48 rex.W
3: 48 89 d8 mov %rbx,%rax
6: 4c 29 e0 sub %r12,%rax
9: 48 89 c1 mov %rax,%rcx
c: 48 c1 f9 02 sar $0x2,%rcx
10: 48 c1 e8 3f shr $0x3f,%rax
14: 48 01 c8 add %rcx,%rax
17: 48 83 e0 fe and $0xfffffffffffffffe,%rax
1b: 4d 8d 3c 44 lea (%r12,%rax,2),%r15
1f: 4c 89 f8 mov %r15,%rax
22: 48 c1 e8 03 shr $0x3,%rax
26: 0f b6 04 10 movzbl (%rax,%rdx,1),%eax
* 2a: 84 c0 test %al,%al <-- trapping instruction
2c: 75 3e jne 0x6c
2e: 4d 63 2f movslq (%r15),%r13
31: 4d 01 fd add %r15,%r13
34: 4c 89 ef mov %r13,%rdi
37: 4c 89 f6 mov %r14,%rsi
3a: e8 48 dc 4b 00 call 0x4bdc87
3f: 49 rex.WB


---
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